The present invention relates generally to the molding articles having a multi-material composition, wherein such materials have different hardnesses or other characteristics. More specifically, the present invention finds particularly advantageous applicability in the manufacture of padded products such as vehicle interior panels.
In the past, multi-material composite structures such as vehicle interior door panels and the like were constructed using a plurality of discrete parts or portions of the composite panel that were assembled in a piece-by-piece manner during installation. Such constructions were found to be very expensive and inconvenient to manufacture and to install. More recently, however, it was found that such composite panels could be manufactured by stretching a sheet material composed of vinyl, for example, over a recessed cavity in a female mold member. The sheet material was then heated and pulled into the female cavity by applying a vacuum between the sheet material and the female mold member. The female mold cavity was then closed off with a male mold member and a moldable material, such as polyvinylchloride or polyurethane, was injected into the space between the sheet material and the male mold member. The pressure of the injection of the moldable material was found to more tightly urge the sheet material into contact with the recessed cavity of the female mold member, thereby enhancing the conformity of the sheet material with the female mold cavity.
The molding technique described above provided for the fabrication of a composite molded panel having an outer skin backed with a molded material, and thus represented a significant advancement in the fabrication technology for such composite panels. However, the advantages of this technique were not fully realized in applications wherein the panel was required to have different hardnesses or other characteristics at different locations thereon. In such applications, the technique described above did not eliminate the need for the expensive manufacturing of separate portions of the overall panel, which were required to be assembled in a piece-by-piece manner during installation. Therefore, although the above-discussed technique constituted a significant advancement, many of the previous problems in manufacturing and assembling such composite articles, with different characteristics at different locations thereon, were not overcome. Accordingly, the need became apparent to provide such composite panels or other molded articles that could be produced in a single, integrated operation and that could yield a one-piece composite article adapted for one-step installation in a vehicle or the like.
According to the present invention, a composite molded article is formed by providing a mold assembly having male and female molds with respective male and female molding surfaces. A deformable sheet material, such as vinyl or other such materials, is positioned on the female molding surface and vacuum-formed, either with or without preheating, in order to draw and conform the heated sheet material into the female mold surface. The male mold member is closed and tightly clamped onto the female mold member, which can be done either before or after the above-mentioned vacuum-forming of the sheet material. A first moldable material having certain predetermined characteristics is introduced into the mold assembly between the male mold surface and the conformed sheet material in order to form a preferably rigid substrate.
It has also been found that certain deformable sheet materials, such as certain foam-backed materials produced by DeWitte Lietaer for example, can be deformed into conformity with the female mold surface by cold flowing without the need for preheating or vacuum forming. Such cold flowing occurs during the introduction of the above-mentioned first moldable material.
During the introduction of the first moldable material, in the present invention, at least one predetermined area of the previously or simultaneously conformed sheet material is blocked off in order to substantially prevent the first moldable material from contacting such predetermined area of the sheet material. Finally, a second moldable material is introduced into the mold assembly between the male mold surface and the sheet material, at least at the previously-blocked off predetermined areas, and the mold assembly is opened to allow removal of the composite molded article after curing of the moldable materials.
The blocking off of the above-mentioned predetermined areas of the conformed sheet material can be accomplished by positioning a plug member or members in contact with the predetermined area or areas of the sheet material prior to the introduction of the first moldable material, with the plug member being removed prior to introduction of the second moldable material. In various embodiments of the present invention, the plug member or members can be removably inserted into the mold assembly between the male mold member and the sheet material, or can be movably interconnected with the male mold member for extension toward, and retraction away from the female mold member. By using the appropriate size, configuration and number of such plug members, the one-piece composite molded article can be fabricated during a process that integrates a number of steps into a single operation in order to produce a composite molded article having virtually any number of different configurations having different characteristics at various locations on the molded article. As a result, such a composite, one-piece molded article can be installed in a vehicle interior, or in other applications, in a single operation, thereby greatly contributing to the speed, simplicity, and economy of manufacture and installation of such an article.
Additional objects, advantages, and features of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings.